Conventionally, image outputs of DVD, satellite broadcast, and the like are commonly output by interlaced scanning so that the video outputs can be reproduced by an image receiver. Recently, image signal reproducing apparatuses for converting interlaced scanned image signals into progressive scanned signals are being introduced as monitors and projectors compatible with multi-scanning, or monitors for computers are becoming widespread.
FIG. 39 is a block diagram showing a configuration of a conventional image signal reproducing apparatus. In FIG. 39, reference numeral 1 denotes a disk on which a main image signal and a determination flag are recorded in an encoded and modulated signal form suitable for recording in advance. The main signal is either an image signal obtained by converting a film material into an electrical signal or an image signal of which material is a video signal. The determination flag shows whether the main image signal is of film material or video material. Reference numeral 2 denotes a pickup which converts the signal recorded on the disk 1 into an electrical signal. Reference numeral 3 denotes a disk rotating device which rotates the disk 1 at a certain revolution-per-minute suitable for the disk 1. Reference numeral 4 denotes an interlaced scanned video signal reproduction circuit which demodulates and decodes the main image signal recorded on the disk 1, and outputs the resultant signal as an interlaced scanned image signal. Reference numeral 5 denotes a first memory which functions as a buffer memory when the interlaced scanned image signal is reproduced. Reference numeral 6 denotes an NTSC encoder which converts the interlaced scanned image signal into an NTSC video format and outputs the result. Reference numeral 7 denotes an interlaced scanned image output terminal through which the reproduced interlaced scanned image output is output. Reference numeral 8 denotes a first material determination circuit which reads the determination flag recorded on the disk 1 from an output of the pickup 2. Reference numeral 9 denotes a field repeat signal generating circuit which generates a field repeat signal when the interlaced scanned image signal reproduction circuit 4 converts the main image signal into an interlaced scanned image signal in the case when the main image signal is of film material. Reference numeral 10 denotes a progressive scanning conversion circuit which converts an output of the interlaced scanned image signal reproduction circuit 4 into a progressive scanned image signal and outputs the result. Reference numeral 11 denotes a second memory which is capable of storing a field of image signal and which is used in the operation of the progressive scanning conversion circuit 10. Reference numeral 12 denotes a D/A converter which converts an output of the progressive scanning conversion circuit 10 into an analog value and outputs the result. Reference numeral 13 denotes a progressive scanning image output terminal through which the progressive scanned image signal is output to an image display apparatus not shown.
The operation of the conventional image signal reproduction apparatus thus constructed will be described.
FIG. 40 is a schematic diagram showing structures of the interlaced scanned image signal and the progressive scanned image signal in the conventional image signal reproduction apparatus. In the interlaced scanned image signal, one field of image is created in 1/60 second. One frame of image is composed of two fields. The number of vertical pixels of each of the two fields is 240. The pixels of one field are buried between the other fields in the vertical direction, vice versa. In the progressive scanned image signal, one frame is created in 1/60 second and the number of pixels in the vertical direction is 480.
Both signals have a vertical frequency of 1/60 second. The number of horizontal scanning lines of the progressive scanned image signal is twice as many as that of the interlaced scanned image signal. The horizontal scanning frequency of the interlaced scanned image signal is about 15.75 KHz, while that of the progressive scanned image signal is about 31.5 KHz.
FIG. 41 is a schematic signal diagram showing a structure of the image signal recorded in the disk 1 of the conventional image signal reproduction apparatus. As shown in FIG. 41, the image signal recorded in the disk 1 has two forms. Specifically, FIG. 41a) shows a film material. In this case, the original material is a film image composed of 24 frames of pictures per second. Each frame of the film image is compressed and recorded onto the disk 1 as an image of 720×480 dots. FIG. 41b) shows a video material image. In this case, the original material is an interlaced scanned image composed of 30 frames/60 fields per second. Each frame is an image of 720×480 dots, but interlaced, so that each field is an image of 720×240 dots. The field is compressed and recorded onto the disk 1. As shown in FIG. 41, the determination flag, which shows whether the main image signal is of film material or video material, is recorded on the disk 1 along with the main video signal.
FIG. 42 is a schematic signal diagram showing a reproduced signal from a film material disk of the conventional image signal reproduction apparatus.
When the material of the image signal recorded in the disk 1 is a film, 24 frames of images of 720×480 dots per second are recorded. The interlaced scanned image signal reproduction circuit 4 reads the signal recorded on the disk 1 from an output of the pickup 2. A first material determination circuit 8 reads the determination flag from an output of the pickup 2 and determines the type of the main image signal, and outputs the resultant type as a determination signal to the interlaced scanned image signal reproduction circuit 4 and the field repeat signal generation circuit 9. Based on an output of the first material determination circuit 8, the interlaced scanned image reproduction circuit 4 recognizes that the main image signal recorded in the disk 1 is of film material. As shown in FIG. 42, the film material images are recorded in the disk 1 in order of the frame numbers . . . , n, n+1, n+2, n+3, . . . . The film material signal thus recorded is converted into an interlaced scanned image and output by the interlaced scanned signal reproduction circuit 4. This is because television monitors are commonly used as an image display apparatus for home entertainment, and the display format is the interlaced scanning. Since the television monitor is designed to display a moving image of 30 frames/60 fields per second, the interlaced scanning video signal reproduction circuit 4 converts 24 frames of images per second into 30 frames/60 fields per second and outputs the result. The interlaced scanning video signal reproduction circuit 4 divides each frame of recorded information into two interlaced scanned field images, odd and even, as shown in the interlaced scanned reproduced image signal in FIG. 42. The interlaced scanning video signal reproduction circuit 4 further displays the head field after the last field of each frame in response to the field repeat signal repeated every 5 fields output from the field repeat signal generation circuit 9 so that 24 frames of film images per second are converted into the interlaced scanned images of 30 frames/60 fields per second which are output. The first memory 5 functions as a buffer memory when the interlaced scanning video signal reproduction circuit 4 reproduces an image. The interlaced scanning video signal reproduction circuit 4 outputs a breakpoint between frames of the interlaced scanned image signal thus generated as the field repeat signal to the progressive scanned conversion circuit 10 as shown in FIG. 12. The NTSC encoder 6 produces an NTSC standard video signal from the interlaced scanned image signal thus reproduced and outputs the result through the interlaced scanned image output terminal 7. A television monitor (not shown) is connected to the interlaced scanned image output terminal 7 so that the user can see the film material image converted into the interlaced scanned image on the monitor.
Further, the interlaced scanned image signal reproduced circuit 4 inputs the interlaced scanned image signal to the progressive scanning conversion circuit 10. The progressive scanning conversion circuit 10 recognizes that the input digital image signal is of film material, based on the presence or absence of the field repeat signal output of the field repeat signal generation circuit 9. Specifically, when the main image is of film material, the field repeat signal output from the field repeat signal generation circuit 9 changes to a 5 field period as shown in FIG. 12. Such a change is detected, and it is determined that the main image is the film material. Accordingly, the progressive scanned image conversion is performed. In the case of the film material, for each frame of each material, the original image of 720×480 dots is divided into two fields of 720×240 dots. Therefore, these fields are synthesized again. Accordingly, the progressive scanning conversion circuit 10 can detect the timing of switching of the frame of the film signal which is a material of the input digital image signal, based on the field repeat signal shown in FIG. 42. The progressive scanning conversion circuit 10 stores the head field of the progressive scanning conversion circuit input shown in FIG. 42 in the second memory 11 and thereafter stores the second field in the second memory 11, and reads both information for each line at a double speed, thereby obtaining the progressive scanning conversion output shown in FIG. 42. The converted image signal is converted into an analog signal by the D/A converter 12, and the resultant analog signal is output through the progressive scanned image signal output terminal 13. A television monitor (not shown) for the progressive scanned image signal is connected to the progressive scanned image signal output terminal 13. The user can see the film material images restored to the progressive scanned image via the television monitor.
FIG. 43 is a schematic signal diagram showing a reproduced signal of the conventional video material disk.
In the case when the material of image signals recorded in the disk 1 is video, an interlaced scanned image of 30 frames/60 fields per second is recorded as recorded information, each field having a 720×240 dots image as shown in FIG. 43. The interlaced scanned image signal reproduction circuit 4 reads the signal recorded in the disk 1 from an output of the pickup 2. The first material determination circuit 8 reads the determination flag from the output of the pickup 2 and determines the type of the main image signal, and outputs the determination flag as the determination signal to the interlaced scanned image signal reproduction circuit 4 and the field repeat signal generation circuit 9. As shown in FIG. 43, the video material images are recorded in the disk 1 in order of the frame numbers . . . , m, m+1, m+2, m+3, m+4, . . . . The interlaced scanned image signal reproduction circuit 4 outputs the video material signal thus recorded as the interlaced scanned image signal shown in FIG. 43 without alteration. The first memory 5 functions as a buffer memory when the interlaced scanned image signal reproduction circuit 4 reproduces an image.
The NTSC encoder 6 produces an NTSC standard video signal from the interlaced scanned image signal thus reproduced and outputs the result through the interlaced scanned image output terminal 7. A television monitor (not shown) is connected to the interlaced scanned image output terminal 7 so that the user can see the film material image converted into the interlaced scanned image via the monitor.
Further, the interlaced scanned image signal reproduced circuit 4 inputs the interlaced scanned image signal to the progressive scanning conversion circuit 10. The progressive scanning conversion circuit 10 recognizes that the input digital image signal is of video material, based on the presence or absence of the field repeat signal output of the field repeat signal generation circuit 9. Specifically, when the main image is of video material, the field repeat signal output from the field repeat signal generation circuit 9 keeps a 5 field period as shown in FIG. 43. Such a situation is detected, and it is determined that the main image is the video material. Accordingly, the progressive scanned image conversion is performed while the main image signal is regarded as the video material. In the case of the video material, the progressive scanning conversion circuit 10 generates a progressive scanned image signal using two pieces of field information, i.e., current field image information and the previous field. In this case, the progressive scanning conversion circuit 10 also uses data for the previous field to interpolate in the vertical direction with respect to pixels having small movements between the current and previous fields of the progressive scanned conversion circuit input shown in FIG. 43. With respect to pixels having large movements between the current and previous fields, vertical interpolated data is generated from upper and lower pixel data in the same field to obtain a progressive scanning conversion circuit output shown in FIG. 43. The converted image signal is converted into an analog signal by the D/A converter 12. The analog signal is output through the progressive scanned image signal output terminal 13. A television monitor (not shown) for the progressive scanned image signal is connected to the progressive scanned image signal output terminal 13 so that the user can see the video material image converted into the progressive scanned image via the monitor.
FIG. 44 is a schematic signal diagram showing a reproduced signal from a disk, which is a film material disk partially including a recorded video signal, of the conventional image signal reproduction apparatus.
Even when the signal source is of film material, part of the signal source may be recorded as a video signal. This happens as follows. A film material may initially be recorded in a video or the like before being recorded on the disk 1. When the material as video is restored to 24-frame information again, part of the material remains as video and is recorded in the disk 1. Specifically, when information to be recorded in the disk 1 is generated, a breakpoint between the frames of the original picture in the recorded video is found by detecting a matching every 5 fields in the material recorded in the video of 60 fields, and the video is restored to 24-frame information which is in turn recorded on the disk 1. Therefore, when noise or the like occurs in the information in the video, the detection of a matching every 5 fields is not successful. The video information remains as it is, and is still recorded on the disk.
In FIG. 44, the nth frame and the n+1th frame in the recorded information are recorded as film material while the n+2th frame to the n+6th frame are recorded as video information. The n+7th frame and thereafter are recorded as film material. When such a disk is reproduced by the conventional image information reproduction apparatus, the nth frame, the n+1th frame, and the n+2th frame are processed as film information. However, since a field repeat signal existing originally is not detected in the even field of the n+3th frame, the progressive scanning conversion circuit 10 determines that the n+3th frame is of video material and thereafter performs the progressive scanning conversion for up to the n+7th frame as video material. The progressive scanning conversion circuit 10 starts performing the progressive scanning conversion again from the n+8th frame as video material. Specifically, in a portion indicated by A in FIG. 44, although the material is actually film, the progressive scanning conversion circuit 10 operates, recognizing the material as video. Thus, the progressive scanning conversion is not optimized.
In such an image signal reproduction apparatus, optimized progressive scanning conversion cannot be performed for an image signal of film material which has been partially recorded as a video signal of 60 fields per second as described above, causing the picture quality to be reduced. This is a drawback for the image signal reproduction apparatus. Accordingly, there is a demand for an image signal reproduction apparatus capable of applying progressive scanning conversion suitable for film material to an image signal of film material which has been partially recorded as a video signal of 60 fields per second.
Conventionally, image outputs of reproduction only disks such as a digital versatile disk (hereinafter referred to as DVD) and CD, magneto-optical disks for recording using optical and magnetic means (hereinafter generically referred to as optical disks), satellite broadcast, ground-based broadcast, and the like are commonly output by interlaced scanning so that the video outputs can be reproduced by an image receiver. Recently, image signal reproducing apparatuses for converting interlaced scanned image signals into progressive scanned signals are being introduced as monitors and projectors compatible with multi-scanning, or monitors for computers is becoming widespread.
FIG. 45 is a block diagram showing a configuration of a conventional image signal reproducing apparatus. In FIG. 45, reference numeral 201 denotes a disk on which either an image signal obtained by converting a film material image into an electrical signal or an image signal of which material is a video signal is recorded in an encoded and modulated signal form suitable for pre-recording in advance. Reference numeral 202 denotes a pickup which converts the signal recorded on the disk 201 into an electrical signal. Reference numeral 203 denotes a disk rotating device which rotates the disk 201 at a certain revolutions-per-minute suitable for the disk 201. Reference numeral 204 denotes an interlaced scanned video signal reproduction circuit which demodulates and decodes the image signal recorded on the disk 201, and outputs the resultant signal as an interlaced scanned image signal. Reference numeral 205 denotes an NTSC encoder which converts the interlaced scanned image signal into an NTSC video format and outputs the result. Reference numeral 206 denotes an interlaced scanned image output terminal through which the reproduced interlaced scanned image is output. Reference numeral 207 denotes a progressive scanned image signal conversion circuit which converts an output of the interlaced scanned image signal reproduction circuit 204 into a progressive scanned image signal and outputs the result. Reference numeral 208 denotes a first memory which is capable of storing a field of image signals and which is used in the operation of the progressive scanned image signal conversion circuit 207. Reference numeral 209 denotes a color difference converter which converts an output of the progressive scanned image signal conversion circuit 207 into a progressive scanned color difference signal and outputs the result. Reference numeral 210 denotes a progressive scanning image output terminal through which the progressive scanned image signal is output to an image display apparatus not shown.
The operation of the conventional image signal reproduction apparatus thus constructed will be described with reference to FIGS. 46 through 50.
FIG. 46 is a schematic diagram showing structures of the interlaced scanned image signal and the progressive scanned image signal in the conventional image signal reproduction apparatus. In the interlaced scanned image signal, one field of image is created in 1/60 second. One frame of image is composed of two fields. The number of vertical pixels of each of the two fields is 240. The pixels of one field are buried between the other fields in the vertical direction, vice versa. In the progressive scanned signal, one frame is created in 1/60 second and the number of pixels in the vertical direction is 480. Both have a vertical frequency of 1/60 second. The number of horizontal scanning lines of the progressive scanned image signal is twice as many as that of the interlaced scanned image signal. The horizontal scanning frequency of the interlaced scanned image signal is about 15.75 KHz, while that of the progressive scanned image signal is about 31.5 KHz.
FIG. 47 is a schematic signal diagram showing a structure of an image signal recorded in the disk 201 of the conventional image signal reproduction apparatus. As shown in FIG. 47, the image signal recorded in the disk 201 has two forms. Specifically, FIG. 47a) shows a film material. In this case, the original material is a film image composed of 24 frames of pictures per second. Each frame of the film image is compressed and recorded onto the disk 201 as an image of 720×480 dots. FIG. 47b) shows a video material image. In this case, the original material is an interlaced scanned image composed of 30 frames/60 fields per second. Each frame is an image of 720×480 dots, but is interlaced, so that each field is an image of 720×240 dots. The field is compressed and recorded onto the disk 201.
When the material of the image signal recorded in the disk 201 is a film, 24 frames of images of 720×480 dots per second are recorded as recorded information. The interlaced scanned image signal reproduction circuit 204 reads the signal recorded on the disk 201 from an output of the pickup 202. As shown in FIG. 47a-1), the film material images are recorded in the disk 201 in order of the frame numbers . . . , n, n+1, n+2, n+3, . . . .
The film material signal thus recorded is modulated and converted into an interlaced scanned image and output by the interlaced scanned signal reproduction circuit 204. This is because television monitors are most commonly used as an image display apparatus for home entertainment, and the display format is the interlaced scanning. Since the television monitor is designed to display a moving image of 30 frames/60 fields per second, the interlaced scanning video signal reproduction circuit 204 converts 24 frames of images per second into an interlaced scanned image of 30 frames/60 fields per second and outputs the result.
Specifically, the interlaced scanning video signal reproduction circuit 204 divides each frame of recorded information into two interlaced scanned field images, odd and even, as shown in the interlaced scanned reproduced image output in FIG. 47a-2). The interlaced scanning video signal reproduction circuit 204 further displays the head field after the last field of each frame so that 24 frames of film images per second are converted into the interlaced scanned images of 30 frames/60 fields per second which are output. The NTSC encoder 205 produces an NTSC standard video signal from the interlaced scanned image signal thus reproduced, and outputs it through the interlaced scanned image output terminal 206. A television monitor (not shown) is connected to the interlaced scanned image output terminal 206 so that the user can see the film material image converted into the interlaced scanned image on the monitor.
Further, the interlaced scanned image signal reproduced circuit 204 inputs the interlaced scanned image signal to the progressive scanned image signal conversion circuit 207. The progressive scanned image signal conversion circuit 207 stores the head field of the progressive scanning conversion circuit input shown in FIG. 47a-2) in the first memory 7 and thereafter stores the second field in the first memory 7, and reads both information for each line at a double speed, thereby obtaining the progressive scanning conversion output shown in FIG. 47a-3). The converted image signal is converted into an analog signal by the color difference converter 209, and the resultant analog signal is output through the progressive scanned image signal output terminal 210. A television monitor (not shown) for the progressive scanned image signal is connected to the progressive scanned image signal output terminal 210. The user can see the film material images restored to the progressive scanned image via the television monitor.
In the case when the material of image signals recorded in the disk 201 is video, an interlaced scanned image of 30 frames/60 fields per second is recorded as recorded information, each field having a 720×240 dots image. The interlaced scanned image signal reproduction circuit 204 reads the signal recorded in the disk 201 from an output of the pickup 202, and modulates the signal and outputs the modulated signal as the interlaced scanned image signal shown in FIG. 47b-2) without alteration.
The NTSC encoder 205 produces an NTSC standard video signal from the interlaced scanned image signal thus reproduced and outputs it through the interlaced scanned image output terminal 206. A television monitor (not shown) is connected to the interlaced scanned image output terminal 206 so that the user can see the film material image converted into the interlaced scanned image via the monitor.
Further, the interlaced scanned image signal reproduced circuit 204 inputs the interlaced scanned image signal to the progressive scanned image signal conversion circuit 207. In the case of the video material, the progressive scanning conversion circuit 207 generates a progressive scanned image signal using two pieces of field information, i.e., current field image information and the previous field. In this case, the progressive scanned image signal conversion circuit 207 also uses data for the previous field to interpolate in the vertical direction with respect to pixels having small movements between the current and previous fields of the progressive scanned conversion circuit output shown in FIG. 47b-2). With respect to pixels having large movements between the current and previous fields, vertical interpolated data is generated from upper and lower pixel data in the same field to obtain a progressive scanning conversion circuit output shown in FIG. 47b-3). The converted image signal is converted into an analog progressive scanned color difference signal by the color difference converter 209. The analog progressive scanned color difference signal is output through the progressive scanned image signal output terminal 210. A television monitor (not shown) for the progressive scanned image signal is connected to the progressive scanned image signal output terminal 210 so that the user can see the video material image converted into the progressive scanned image via the monitor.
FIG. 48 is a schematic diagram showing the vertical frequency characteristics of materials for the conventional image signal reproduction apparatus. In the case of the video material to be interlaced scanned, each field has 240 lines, two fields having 480 lines. In the case of the film material, optical information recorded on the original film is converted into electrical information of 480 lines of progressive scanned signals. Therefore, the vertical frequency characteristics are of a high band region indicated by the characteristics of the film material shown in FIG. 48. The film material image is supposed to be reproduced by the interlaced scanned receiver. Bandwidth is limited in advance in order to avoid feedback interference. As indicated by the characteristics of the film material after removing interlace interference, the vertical frequency characteristics are reduced to the same level as that of the characteristics of the video material, at which level the film material image is recorded.
FIG. 49 is a schematic diagram showing the vertical frequency characteristics of a progressive scanned image output for the conventional image signal reproduction apparatus. As shown in FIG. 49, the vertical frequency characteristics after conversion into the progressive scanned image output are inferior to the characteristics of the original film material.
FIG. 50 is a schematic diagram showing the frequency characteristics of visual appreciation of the interlaced scanned image and the progressive scanned image output of the conventional image signal reproduction apparatus. In general, a progressive scanning image monitor has twice as many the number of the horizontal scanning frequency as that of an interlaced scanning image monitor. Therefore, the electrical and optical frequency bands required to attain the same resolution needs to be doubled. The double number of scanning lines leads to a characteristic in which visual impression is low resolution. Therefore, comparing the interlaced scanned image signal with the image signal obtained by converting the interlaced scanned image signal into the progressive scanned image signal, the latter image signal gives the user the impression that the frequency characteristics are poorer. Particularly, in the conventional image signal reproduction apparatus, the interlaced scanned image and the progressive scanned image are output at the same time. Therefore, both images can be easily compared with each other, so that a large difference between both images would be a large drawback for the image signal reproduction apparatus.
In such an image signal reproduction apparatus, there is a problem in that, as described above, with respect to the film material image signal, the vertical frequency after the progressive scanning conversion has characteristics significantly inferior to the characteristics of the original film. There is also a problem in that there is the visual impression that the picture quality after the progressive scanning conversion has lower resolution than that of the picture quality after the interlaced scanning.
Accordingly, there is a demand for introduction of an image signal reproduction apparatus capable of outputting a progressive scanned signal which has resolution close to that of the original film after the progressive scanning conversion and has resolution which is not visually degraded as compared with the interlaced scanned image.
Conventionally, image outputs of DVD, satellite broadcast, and the like are commonly output by interlaced scanning so that the video outputs can be reproduced by an image receiver. Recently, image signal reproducing apparatuses for converting interlaced scanned image signals into progressive scanned signals are being introduced as monitors and projectors compatible with multi-scanning, or monitors for computers is becoming widespread.
FIG. 51 is a block diagram showing a configuration of an image signal reproducing apparatus which is a conventional example of the technologies related to the present invention. The image signal reproducing apparatus includes an image signal and a determination flag for determining the aspect ratio of the image signal, and reproduces an information signal recorded on a disk. In FIG. 51, reference numeral 301 denotes a disk on which an image signal and the determination flag indicating the aspect ratio of the image signal are recorded in an encoded and modulated signal form suitable for recording (or reproduction) in advance. Reference numeral 302 denotes a pickup which converts the signal recorded on the disk 301 into an electrical signal. Reference numeral 303 denotes a disk rotating device which rotates the disk 301 at a certain revolutions-per-minute suitable for the disk 301. Reference numeral 304 denotes an interlaced scanned video signal reproduction circuit which demodulates and decodes the image signal recorded on the disk 301, and outputs the resultant signal as an interlaced scanned image signal. Reference numeral 305 denotes a material determination circuit which reads the determination flag recorded on the disk 301 from an output of the pickup 302.
Reference numeral 306 denotes a first aspect ratio conversion circuit which is controlled by the first control circuit 312 and which converts the aspect ratio of the input image signal and outputs the result. Reference numeral 307 denotes an NTSC encoder which converts the interlaced scanned image signal into an NTSC video format and outputs the result. Reference numeral 308 denotes an interlaced scanned image output terminal through which the reproduced interlaced scanned image is output to a monitor (not shown) for the interlaced scanned image signal.
Reference numeral 309 denotes a progressive scanned image signal conversion circuit which converts an output of the first aspect ratio conversion circuit 306 into a progressive scanned image signal and outputs the result. Reference numeral 310 denotes a color difference converter which converts an output of the progressive scanned image signal conversion circuit 309 into an analog color difference signal and outputs the result. Reference numeral 311 denotes a progressive scanning image output terminal through which the progressive scanned image signal is output to a monitor (not shown) for the progressive scanning image.
Reference numeral 312 denotes a first control circuit which controls the first aspect ratio conversion circuit 306 using an output of the material determination circuit 305 and an output of a first aspect ratio setting section 313. Reference numeral 313 denotes the first aspect ratio setting section which is used by the user to set the aspect ratio of the receiver.
The operation of the conventional image signal reproduction apparatus thus constructed will be described with reference to FIGS. 52 through 60.
FIG. 52 is a schematic diagram showing structures of the interlaced scanned image signal and the progressive scanned image signal in disk 301 in the conventional image signal reproduction apparatus. In the interlaced scanned image signal, one field of image is created in 1/60 second. One frame of image is composed of two fields. The number of vertical pixels of each of the two fields is 240. The pixels of one field are buried between the other fields in the vertical direction, vice versa. In the progressive scanned signal, one frame is created in 1/60 second and the number of pixels in the vertical direction is 480. Both have a vertical frequency of 1/60 second. The number of horizontal scanning lines of the progressive scanned image signal is twice as many as that of the interlaced scanned image signal. The horizontal scanning frequency of the interlaced scanned image signal is about 15.75 KHz, while that of the progressive scanned image signal is about 31.5 KHz.
FIG. 53 is a schematic signal diagram showing the aspect ratio of an image signal of the conventional image signal reproduction apparatus. As shown in FIG. 53a), the image signal of image source recorded in the disk 301 has three forms. Specifically, FIG. 53a)a-1) shows a material having information which fills a full screen of 4:3 (hereinafter referred to as a 4:3 full image). FIG. 53a)a-2) shows a material having an image of 16:9 in the middle of the 4:3 screen, the upper and lower portions being shaded (hereinafter referred to as a 4:3 letterbox image). FIG. 53a)a-3) shows a material having information which fills a full screen of 16:9 (hereinafter referred to as a 16:9 full image).
FIG. 53b) shows the aspect ratio of the monitor for the interlaced scanned image signal. As shown in FIG. 53b), there are two types of monitor for the interlaced scanned image signal, one type shown in FIG. 53b)b-1) having an aspect ratio of 4:3 and the other shown in FIG. 53b)b-2) having an aspect ratio of 16:9.
FIG. 53c) shows the aspect ratio of the monitor for the progressive scanned image signal. As shown in FIG. 53c), there are two types of monitor for the interlaced scanned image signal, one type shown in FIG. 53c)c-1) having an aspect ratio of 4:3 and the other shown in FIG. 53c)c-2) having an aspect ratio of 16:9.
The interlaced scanned image signal reproduction circuit 304 reads a signal recorded on the disk 301 from an output of the pickup 302, reproduces the interlaced scanned image signal, and outputs the result to the first aspect ratio conversion circuit 306. The material determination circuit 305 reads the determination flag from an output of the pickup 302, determines the type of the image signal, and outputs the result as the determination signal to the first control circuit 312.
The user sets the aspect ratio of a monitor via which the user intends to output the image signal, using the first aspect ratio setting section 313. The first control circuit 312 controls the first aspect ratio conversion circuit 306 using an output of the material determination circuit 305 and an output of the first aspect ratio setting section 313.
FIG. 54 is a schematic diagram for explaining the operation of the first aspect ratio conversion circuit 306 of the conventional image signal reproduction apparatus. Assuming that the monitor has an aspect ratio of 4:3, the first aspect ratio conversion circuit 306 has a function which compresses a material having an aspect ratio of 16:9 in the vertical direction. Specifically, in order to display the 16:9 material on the 4:3 monitor at the correct aspect ratio, 4 lines of information of an input image signal are subjected to a filtering process so that 3 lines of information are generated. Such a process is performed for the entire screen, so that the entire screen is compressed in the vertical direction. In this case, the aspect ratio is correctly converted for the 16:9 screen, but leaves blanks in the upper and lower portions. Such portions are rendered as black images. The aspect ratio conversion function can select a working or non-working state using the first control circuit 312. In the case of the non-working state, the first aspect ratio conversion circuit 306 outputs the input image signal without the aspect ratio conversion.
In FIG. 51, the user sets the aspect ratio of the monitor for display to 4:3 or 16:9 using the first aspect ratio setting section 313. On the other hand, the material determination circuit 305 outputs the aspect ratio of the image source, i.e., whichever it is, the 4:3 full screen or the 4:3 letterbox screen or the 16:9 screen, to the first control circuit 312. The first control circuit 312 causes the aspect ratio conversion operation of the first aspect ratio conversion circuit 306 to be in the non-working state when the aspect ratio of the image source of the material determination circuit 305 is the 4:3 full image or the 4:3 letterbox image. The first control circuit 312 causes the aspect ratio conversion operation of the first aspect ratio conversion circuit 306 to be in the non-working state when the material determination circuit 305 indicates that the aspect ratio of the image source is 16:9 and the first aspect ratio setting section outputs 16:9. Note that the first control circuit 312 causes the aspect ratio conversion operation of the first aspect ratio conversion circuit 306 to be in the working state when the material determination circuit 305 indicates that the aspect ratio of the image source is 16:9 and the first aspect ratio setting section outputs 4:3.
The NTSC encoder 307 converts an output of the first aspect ratio conversion circuit 306 to the NTSC video format. The interlaced scanned image output is output through the interlaced scanned image output terminal 308 to the interlaced scanned image monitor (not shown).
Next, the cases when the image source of the conventional image signal apparatus corresponds to the angle of view of the interlaced scanned image monitor image and when the image source of the conventional image signal apparatus corresponds to the angle of view of the progressive scanned image monitor image, will be described with respect to FIGS. 55 through 57 and FIGS. 58 through 60, respectively, for each of the 4:3 full screen, the 4:3 letterbox image, and the 16:9 image.
FIG. 55 is a schematic diagram for explaining the aspect ratio of an image displayed on the interlaced scanned image monitor in the case of the image source having the 4:3 full image in the conventional image signal reproduction apparatus. As shown in FIG. 55b-1, the correct aspect ratio is displayed on the 4:3 monitor. However, as shown in FIG. 55b-2, the 16:9 monitor does not display the correct aspect ratio, so that the displayed image is extended horizontally. On the other hand, the interlaced scanned image monitor includes a 4:3 output switch function since the standard aspect ratio of the conventional interlaced scanned image signal is 4:3. The interlaced scanned image monitor can display as shown in FIG. 55b-3 at the correct 4:3 aspect ratio using the 4:3 output switch function.
FIG. 56 is a schematic diagram for explaining the aspect ratio of an image displayed on the interlaced scanned image monitor in the case of the image source having the 4:3 letterbox image in the conventional image signal reproduction apparatus. As shown in FIG. 56b-1, the correct aspect ratio is displayed on the 4:3 monitor. However, as shown in FIG. 56b-2, the 16:9 monitor does not display the correct aspect ratio, so that the displayed image is extended horizontally. On the other hand, the interlaced scanned image monitor includes a 4:3 letterbox image output switch function since the standard aspect ratio of the conventional interlaced scanned image signal is 4:3. The interlaced scanned image monitor can display as shown in FIG. 56b-3 at the correct 16:9 aspect ratio using the 4:3 output switch function.
FIG. 57 is a schematic diagram for explaining the aspect ratio of an image displayed on the interlaced scanned image monitor in the case of the image source having the 16:9 image in the conventional image signal reproduction apparatus. As shown in FIG. 57b-1, the aspect ratio with no change is not correctly displayed on the 4:3 monitor, so that the displayed image is extended vertically. However, if the user sets the fact that a monitor to be connected is 16:9, to the first aspect ratio setting section, the first aspect ratio conversion circuit 306 is activated. The aspect ratio is converted so that the image is correctly displayed as shown in FIG. 57b-4. In addition, as shown in FIG. 57b-2, the 16:9 monitor displays the image at the 16:9 aspect ratio.
Specifically, in the conventional image signal reproduction apparatus, the interlaced scanned image monitor can display at the correct aspect ratio any combination of 3 types of image sources, i.e., the 4:3 full image, the 4:3 letterbox image, and the 16:9 image with 2 types image monitor, i.e., the 4:3 monitor and the 16:9 monitor.
An output of the first aspect ratio conversion circuit 306 is input to the progressive scanned image signal conversion circuit 309. The progressive scanned image signal conversion circuit 309 converts the input interlaced scanned image signal to the progressive scanned image signal, and outputs the result. The color difference converter 310 converts the progressive scanned image signal to a color difference image signal, and outputs the progressive scanned image output through the progressive scanned image output terminal 311 to the progressive scanned image monitor (not shown).
FIG. 58 is a schematic diagram for explaining the aspect ratio of an image displayed on the progressive scanned image monitor in the case of the image source having the 4:3 full image in the conventional image signal reproduction apparatus. As shown in FIG. 58c-1, the aspect ratio is correctly displayed on the 4:3 monitor. However, as indicated by c-2 in FIG. 58, the aspect ratio with no change is not correctly displayed on the 16:9 monitor, so that the displayed image is extended horizontally. Here, the progressive scanned image 16:9 monitor is a monitor intended to receive a high-definition television signal, and does not include the 4:3 output mode. The 16:9 standard aspect ratio of the high-definition television signal is not displayed at the correct aspect.
FIG. 59 is a schematic diagram for explaining the aspect ratio of an image displayed on the progressive scanned image monitor in the case of the image source having the 4:3 letterbox image in the conventional image signal reproduction apparatus. As shown in FIG. 59c-1, the aspect ratio is correctly displayed on the 4:3 monitor. However, as indicated by c-2 in FIG. 59, the aspect ratio with no change is not correctly displayed on the 16:9 monitor, so that the displayed image is extended horizontally. As described above, the progressive scanned image 16:9 monitor is a monitor intended to receive a high-definition television signal, and does not include the 4:3 letterbox output mode. The 16:9 standard aspect ratio of the high-definition television signal is not displayed at the correct aspect.
FIG. 60 is a schematic diagram for explaining the aspect ratio of an image displayed on the progressive scanned image monitor in the case of the image source having the 16:9 image in the conventional image signal reproduction apparatus. As shown in FIG. 60c-1, the aspect ratio with no change is not correctly displayed on the 4:3 monitor, so that the displayed image is extended vertically. However, if the user indicates the fact that a monitor to be connected is 16:9, to the first aspect ratio setting section, the first aspect ratio conversion circuit 306 is activated. The aspect ratio is converted so that the image is correctly displayed as shown in FIG. 60c-4. In addition, as shown in FIG. 60c-3, the 16:9 monitor displays the image at the 16:9 aspect ratio.
In other words, in the conventional image signal reproduction apparatus, the progressive scanned image monitor cannot display at the correct aspect ratio a combination of the image sources of the 4:3 full image and the 4:3 letterbox image with the 16:9 image monitor.
As described above, in the conventional image signal reproduction apparatus, there is a problem in that the progressive scanned image monitor cannot display at the correct aspect ratio a combination of the image source of the 4:3 full image or the 4:3 letterbox image with the 16:9 image monitor. Accordingly, there is a demand for an image signal reproduction apparatus in which any combination of the 3 types of image sources, i.e., the 4:3 full image, the 4:3 letterbox image, and the 16:9 image with 2 types image monitor, i.e., the 4:3 monitor and the 16:9 monitor, can be displayed at the correct aspect ratio.
An object of the present invention is to provide an image signal reproduction apparatus which can perform a progressive scanning conversion process suitable for film material with respect to a film material image signal part of which is recorded as a video signal of 60 fields per second. This is achieved by determining the type of material of an image signal by determining whether a main image signal is a first type of image signal or a second type of image signal, based on an output of a field difference detection circuit obtained from an interlaced scanned image signal and another interlaced scanned image signal 2 field before in addition to an output of a material determination circuit.
Another object of the present invention is to provide an image signal reproduction apparatus which can output a progressive scanned image with a resolution close to the original film and with less degradation of resolution compared with the interlaced scanned image even in visual appreciation, after subjecting the film material image signal to progressive scanning conversion.
Still another object of the present invention is to solve the above-described problems with the conventional technology and provide an image signal reproduction apparatus which can display an image at the correct aspect ratio in the case of any combination of image sources having different aspects and monitors having different aspects.